Gas turbine engine hot gas path parts are often manufactured of superalloy materials. The term “superalloy” is used herein as it is commonly used in the art; i.e., a highly corrosion and oxidation resistant alloy that exhibits excellent mechanical strength and resistance to creep at high temperatures. Superalloys typically include a high nickel or cobalt content. Examples of superalloys include alloys sold under the trademarks and brand names Hastelloy, Inconel alloys (e.g. IN 738, IN 792, IN 939), Rene alloys (e.g. Rene N5, Rene 80, Rene 142), Haynes alloys, Mar M, CM 247, CM 247 LC, C263, 718, X-750, ECY 768, 282, X45, PWA 1483 and CMSX (e.g. CMSX-4) single crystal alloys.
FIG. 1 illustrates a known gas turbine engine blade 10 including an airfoil 12, platform 14, and root 16. The blade 10 may be manufactured from a superalloy material, and may be covered by any of several known thermal barrier coating systems. Such blades are known to develop service-induced thermal-mechanical fatigue cracks, such as cracks 18, 20 located on the platform 14. Other forms of service-induced degradation of the superalloy material are possible, and such defects may form in other areas of the blade 10 or in other hot gas path components of the engine.
It is known that superalloy materials are among the most difficult materials to repair due to their susceptibility to weld solidification cracking and strain age cracking. Prior art gas turbine superalloy components such as blade 10 which developed service-induced defects in their superalloy base materials often could not be repaired, resulting in a large expense to replace the component. Cracks in superalloy materials can be repaired with brazing processes, but such repairs are of limited application because of the limited strength of the braze material and because the brazing process typically requires the use of a detrimental melting point depressant material, such as boron or silicon. Thus, improved processes for the repair of superalloy materials are desired.